i

Intermediate wheel:
Part of the motion work. Sits on the intermediate wheel stud and is driven by the cannon pinion.

Invar:
Special Iron-Nickel alloy with 36.8% nickel. Tempered Invar has a thermal expansion ten times less than steel. The alloy was invented by Charles Edouard Guillaume at the end of the 19th century. Sigmund Riefler was the first to use it 1896 as material for pendulum rods in precision clocks.

Impulse:
Process where the driving force is transmitted to the pendulum.

Impulse face:
Inclined plane on the pallets. The tip of the escapement wheel tooth slides along the impulse face and transmits a driving impulse to the pendulum.

Isochronism:
The constancy of the period of the pendulum with changes in amplitude. Only achievable with small changes at low amplitude.

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